Objective:

To investigate the heterogeneity of PARP inhibitor distribution in ovarian tumors and its implications for treatment resistance, with a focus on enhancing clinical outcomes.

Key Findings:

• Marked heterogeneity in drug accumulation across ovarian tumors and within individual tumor slices, highlighting the need for tailored treatment strategies.
• Lysosomes can act as reservoirs for certain PARP inhibitors, creating hotspots of high exposure that may influence treatment outcomes.
• High-drug regions were enriched for apoptotic and DNA damage response signatures, indicating potential pathways for therapeutic targeting.
• Rucaparib colocalized with lysosomes, and altering lysosomal conditions significantly affected drug levels, suggesting a mechanism for resistance.

Interpretation:

Lysosomes play a significant role in the accumulation and release of weak-base PARP inhibitors, potentially influencing treatment efficacy and resistance, which could inform personalized treatment strategies.

Limitations:

• Study conducted on a limited number of patient samples, which may affect the generalizability of the findings.
• Further in vivo studies are needed to validate findings and understand the clinical implications of tumor heterogeneity.

Conclusion:

Understanding the molecular signature of tumors may lead to more personalized therapeutic approaches in ovarian cancer treatment, ultimately improving patient outcomes.